And more will be needed if we do not put energy efficiency first by promoting hydrogen and e-fuels where direct electricity use is possible.
For most road transport, battery electric vehicles will be able to provide the most efficient and cost-effective solution. Battery electric vehicles are twice as efficient as fuel cell vehicles running on hydrogen. Put differently, to drive the same number of kilometers, the amount of renewable energy needed for a fuel cell vehicle is double what is needed for a battery electric vehicle and almost four times, if the vehicle is using liquid efuels in an internal combustion engine. This implies a much greater demand for additional renewable energy to produce the hydrogen and/or efuels needed for the same transport work: For example, if half of heavy-duty trucks were run on hydrogen and half on e-diesel, they would consume 151% more renewables in 2050 than if they were directly electrified.
But there are some transport modes like aviation and shipping where the use of batteries will not be feasible or economically viable. An airplane or a container ship going around the world will require a more energy-dense fuel to cover longer distances. Sustainably produced hydrogen and e-fuels will play a big role in reducing their emissions. Some trucks or bus coaches covering long distances and needing short refueling times may also be powered by fuel cells using hydrogen.
But these fuels can have a carbon footprint worse than the oil they are replacing. This is because hydrogen and e-fuels can be made in different ways. They can be made from fossil gas or via electrolysis.
Almost all hydrogen today is produced from fossil gas (via a process called steam methane reforming). To truly decarbonise transport, we should not use fossil gas to produce hydrogen and other e-fuels. Switching away from oil as transport fuel to use fossil gas to produce hydrogen (using technologies like carbon capture and storage) will leave transport dependent on fossil fuels and its infrastructure.
When electrolysis is used, hydrogen and e-fuels are only as clean as the electricity used. The electrolyser should not be powered by electricity, produced from coal or gas. The same goes for the processes used to produce the e-fuels. The only sustainable and scalable way to produce hydrogen and efuels is to use 100% renewable electricity and, on top of that, make sure that the production of hydrogen and e-fuels does not displace the use of renewable electricity from other sectors.
Scaling up the production of green hydrogen and e-fuels and reducing its costs will take time. Given the price gap with fossil fuels, strong policies will be needed to force shipowners or suppliers of aviation fuels to start using sustainable hydrogen and e-fuels in particular.
For the foreseeable future, hydrogen and efuels will be expensive and available in limited quantities. This is why they should be targeted to planes and ships. To achieve its higher climate targets, the EU is working on several initiatives to increase the share of renewable energy in road transport (Renewable Energy Directive) and the use of sustainably produced hydrogen and efuels in the shipping and aviation sectors (FuelEU Maritime and RefuelEU Aviation).